The ssCART-19 cells showed cell properties similar to those of the regular CAR T-19 cells in terms of the level of transduction efficiency (45.7% vs 38.1%), the ratio of CD4/CD8 (Fig. 2d), proliferation (Fig. 2e) and cytotoxicity as measured by a CD107a (Fig. 2f) degranulation assay or cytotoxicity assay when cocultured with either Raji cells or patient-derived primary B-ALL cells (Fig. 2g). This evidence concerns the gene CD4 and acute lymphoblastic leukemia.